The mechanic seems to have a bunch of challenges, but perhaps the biggest is that successfully Melding seems akin to a Planeswalker going ultimate: its hard and super splashy, but the reward is so powerful that the game will probably end before you actually get to use your new game piece
In that regard, even if you do have luck with card draws and your opponent doesnt break your combos too much, theres still an innate puzzle element forcing you to read your Extra Deck cards thoroughly to make sure you use them right (or, alternately, figure out which ones to summon, and against what)
The explanation for those who don't get the joke in GigaX's comment: "Colorless" is the term used in the Trading Card Game that is primarily used for Normal-type Pokmon from the mainline RPG games
Taking You with Me: Metalrokket Dragon destroys all opponent's cards in the same column and Shelrokket Dragon destroys 1 monster in the same column and all monsters in adjacent zones
But Undead Warchief is still among the very strongest
Inkshield is a purely defensive card, but one that can take you from the cusp of dying to actually winning the game in the next turn cycle